The piece in this book on Abelard and Heloise, that original academic affair that ended worse than badly, is memorable for glorifying the sanctity of her passion over what is correctly called his post-testicular thought. The piece on partings in general goes off on an informative tangent. What do you do when you come to a fork in the road and are faced with a consistent liar and a consistent truth-teller, and you don't know which is which, and you can ask one question about which way to go? You ask one of them to say what the other would say is the right way, and you don't take it.

AC Grayling makes a good argument that reading the novel enlarges our sympathies, to which is added that it is necessary to the good life in the good society. There is an excellent piece on a closeness between two peoples that is indicated by a lot, including "shalom" and "salaam". There are fine pieces on achieving a philosophy of life of the ancient Epicureans, Stoics and the like that will help us with the fact of death to come. There is eloquence on eloquence as distinct from rhetoric.

Not everything in the book is at the heart of things. We learn that Einstein asked Freud "Why War?", and Freud dedicated his answer to Mussolini. We are reminded of Freud's thinking on the blush, which is that it is a facial erection, and also that many of us now take him to be off with the fairies. Pity about the qualification "scientifically speaking".

Grayling is a ruminative fellow beguiled by the possibilities of language and with an inclination to tell you things. It can hardly be a yen, since this is the fourth volume of essays, 78 in this case, each a few pages long. He is opinioned but not opinionated. He is good with words - "romance is the foreplay of foreplay" - and raises the old temptation to think that really good writing is good thinking. Most of the pieces are well above the category of classy journalism. His own and the thoughts of other philosophers are employed. There are succinct obituaries, Plato through Abelard to Bernard Williams.

The official theory of the book is that it is half of an easy conversation, that its pieces do not overwhelm you, the reader, and so allow and prompt your own reflection. Because you've understood, and the conversation is over soon after it begins, you get a chance to think about things. Yes, you do.

The politics on offer is mainly the gentleness and irresolution of liberalism, the wider kind that has Americans in it. It does not ask what follows from our democracy being hierarchic. It asks other questions. How much am I my brother's keeper? Whither the rainforest?

The recommendation for dealing with terrorists is that we keep on taking an attitude to them, regard them with the contempt that is called for by their being moral cretins. I was not overturned by the proposition that what the Palestinians have been doing has been owed to their chosen ideology or faith or to hating other people in the abstract or their culture or their government. I thought it had something to do with the violation of a homeland. He also offers a reassurance that is not reassuring. It is that if terrorists get nuclear bombs they will still only be able to kill a minority of the world's population of six billion, say some hundreds of thousands - a snowball thrown at the castle of our values and our freedom.

Our guide is keen on the ancient world and inclined to think that the miracle cure for our philosophy would be the re-Greeking of it. This leads to seeing what colour you paint your house as a matter of ethics, though not of morality. He is forthright in the philosophy of mind. What people think of as love is a blind biological mechanism for initiating a new generation of human genes. Isn't there the problem that all of feeling and thinking is tied up with some mechanism, biological or otherwise?

He is a philosopher engaged in what he rightly praises, adding value to life, in a way that is not too taxing. It isn't pop philosophy, deep thinking for kiddies, or another guide short enough to be vapid. He is a little inclined to the false antithesis - prompting thought does have more alternatives than overwhelming, coercing or drowning it in excessive detail. That sort of thing is easily put up with. He is much more than the sage of St Hilda's and Birkbeck. Is there a better little introduction to Dostoevsky's The Idiot? A neater report on fences, physical and mental? Here is a book worth talking to.

· Ted Honderich is Grote professor emeritus of the philosophy of mind and logic at University College London. A new edition of his Oxford Companion to Philosophy has just been published